There has been proposed a contactless power supply system that contactlessly supplies power to charge a battery mounted on an electric vehicle. In the contactless power supply system, power is transmitted via a power transmission coil from a power transmission device provided on the ground side and the transmitted power is received by a power reception coil of a power reception device mounted on the vehicle. Then, the received power is supplied to loads, such as a battery and a motor.
In such a contactless power supply system, when a change in the gap between the power transmission coil and the power reception coil or a planar positional shift between the power transmission coil and the power reception coil occurs, the power loss of the power transmission coil increases and the temperature of the power reception device rises due to an increase of this power loss. Therefore, the temperature of the power reception device needs to be monitored.
Patent Literature 1 discloses a temperature control device that estimates the temperature of an electronic device by calculation. In this Patent Literature 1, the temperature is estimated by integrating the quantity of heat on the basis of operation mode information and an operation time. Then, when the estimated temperature reaches a threshold, the operation mode is switched to an operation mode which generates a less amount of heat. However, in Patent Literature 1, the temperature is estimated by detecting the operation mode inside the device, and the influence from an external device is not taken into consideration.